The area above the merge button now contains more information, making it easier to see if your proposed changes are ready to go or need more work.

new merge box

Each month, 119,000 repositories on GitHub use automated status checks (via the GitHub Statuses API) and it’s important that this information is presented in a way that you can easily understand. When you’re ready to merge a pull request, you should be able to see that it is ready. If a check isn’t passing, you should be able to see why.

Here’s a refresher on how to merge a pull request.